We seek to understand how the optical structures and retinular cells of eyes influence and limit the visual information provided to the nervous system by the axons of the retinular cells. We are concerned with mechanisms of spatial, spectral, polarizational, and temporal information processing. We wish to learn how these different aspects of visual objects are separated and the degree to which they are independent. We also consider mechanisms and effects of photo- mechanical adaptation. The theoretical and experimental techniques employed include electromagnetic theory, systems theory, theoretical modeling and computer simulation, reflectance and transmittance microspectrophotometry, behavioural and optomotor studies, electrophysiology, analogue and digital data aquisition and analysis, digital computers, and optical and electron microscopy. Most of this work deals with the compound eyes of insects.